The Messerschmitt Bf 109 was a German World War II fighter aircraft designed by Willy Messerschmitt in the early 1930s. It was one of the first true modern fighters of the era, including such features as an all-metal monocoque construction, a closed canopy, and retractable landing gear. Having gone through its baptism of fire in the Spanish Civil War, the Bf 109 was still in service at the dawn of the jet age at the end of World War II, during which it was the backbone of the German Luftwaffe fighter force. An inverted Vee-piston engined fighter, the Bf 109 was supplemented, but never completely replaced in service, by the radial engined Focke-Wulf Fw 190 from the end of 1941.